Expressing Uncertainty in Spanish with the Imperfect Subjunctive

You always use the Spanish imperfect subjunctive verb tense to express uncertainty about a past action, but several other key words and circumstances can also clue you in to the need for the imperfect subjunctive, like the following:

Verbs such as desear (to wish), prohibir (to forbid), and creer (to believe) used to introduce a subordinate clause concerning an uncertain event that occurred in the past
Expressions of personal opinion about past events that are introduced with que (that)
The conjunctions a fin de que (in order that/so that) and sin que (without)

The following sections explore these circumstances.

Introducing uncertainty with uncertain verbs and conjunctions

Some verbs naturally call for the use of the subjunctive; the following table lists some verbs that, when followed by que, always require the subjunctive in the que clause:

Verb Expressions That Require the Subjunctive
Term	Translation
alegrarse de que	to be happy about something
creer que (only in the affirmative)	to believe
desear que	to wish
impedir que	to prevent
negar que	to deny
pensar que (only in the affirmative)	to think
permitir que	to allow
prohibir que	to forbid
sentir que	to feel
suplicar que	to beg

Conjunctions smooth the transition from the main clause to the subordinate clause. When these conjunctions express uncertainty, they must be followed by the subjunctive. Two conjunctions that always require the use of the subjunctive are a fin de que (in order that, so that) and sin que (without). Here’s a look at a fin de que in action: Ella pidió menos comida a fin de que ellos terminaran a tiempo. (She ordered less food so that they would finish on time.)

Express yourself in uncertain terms

The present subjunctive utilizes some impersonal expressions that require the subjunctive in the dependent clause. Here are some additional expressions in the imperfect tense that require the imperfect subjunctive.

Expressions That Require the Imperfect Subjunctive
Imperfect Expression	Translation
era menester que	it was necessary that
era preciso que	it was mandatory that
era urgente que	it was urgent that
era natural que	it was natural that
era justo que	it was fair that
era interesante que	it was interesting that
era mejor que	it was better that
convenía que	it was suitable that
importaba que	it was important that
parecía mentira que	it was hard to believe that

Using the imperfect subjunctive with if, as if, and as though

The word if is packed to the gills with uncertainty; hence, it always calls for the use of the subjunctive: Si yo fuera más inteligente, iría a la universidad. (If I were smarter, I would go to college.)

In this example, you’re starting the sentence with the subordinate clause, which requires that were be in the imperfect subjunctive. The main clause, I would go to college, is in the indicative.

In Spanish, the phrase as if implies a sense that you’re assuming something is true. To say as if or as though in Spanish, you use the expression como si. When a subordinate clause begins with como si, the verb is in the imperfect subjunctive. The main clause can either be in the present, the past, or the conditional. Here are some examples of sentences using como si.

Ella actuaba como si ganara el premio. (She acted as though she had won the prize.)
Él hablaba como si supiera todas las respuestas. (He talked as if he knew all of the answers.)